[Snort-users] Unable to configure unified2 output

Mike Lococo mikelococo at ...11827...
Tue Mar 30 18:19:44 EDT 2010


I recently attempted to migrate to merged alert/log unified2 output 
using the following config:

   output unified2: filename snort-unified2.log, limit 128

When running this config I get snort.log.[epochtime] files instead of 
the snort-unified2.log.[epochtime] files that I expect.  The snort.log 
files are tcpdump formatted... not unified2.  It's not clear to my why 
this config doesn't work, it should be valid according to the manual and 
to many mailing-list examples.

If I make a trivial change to the config above...

   output log_unified2: filename snort-unified2.log, limit 128

... the tcpdump-formatted files are no longer created, and I do see 
snort-unified2.log.[epochtime] files as expected.  However, I'd like to 
have a "merged" unified2 log with both alert and log information in it 
as is specified in the previous "broken" config.

If I run snort with no output-line configured at all, I get the same 
tcpdump-formatted snort.log files as I get with my broken unified2 
config, which makes me think that there is something causing my config 
line to be ignored and I'm falling through to a default.

My initial configuration used the original unified "log" output and 
behaves as expected:

   output log_unified: filename snort0.log, limit 128

This created the expected snort0.log.[epochtime] files in 
/var/log/snort, and has worked well for quite some time.  I can switch 
back to this config now and it still works as expected, so I feel fairly 
confident in the rest of my snort config/infrastructure.

Additional possibly relevant info:
* I'm running the latest stable snort ( - Build 124).
* When running snort from the command line, I don't see any useful 
output printed to the screen in any of my test cases.  The only relevant 
line appears to be "Initializing Output Plugins!", which never changes 
or echoes the output configuration that is being initialized.
* A similar problem was reported in the forum in November with no 

Does anyone have any ideas about what could be going wrong, or 
additional troubleshooting steps to take?  Since there's no error or 
problem indicator (other than failure to produce the desired logs) I'm 
not sure what to check next.

Mike Lococo

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